US3956572A - Cooling means for electric arc furnaces - Google Patents

Cooling means for electric arc furnaces Download PDF

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Publication number
US3956572A
US3956572A US05/557,415 US55741575A US3956572A US 3956572 A US3956572 A US 3956572A US 55741575 A US55741575 A US 55741575A US 3956572 A US3956572 A US 3956572A
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US
United States
Prior art keywords
shell
furnace
chamber
invention defined
heat conductive
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US05/557,415
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English (en)
Inventor
Ronald D. Gray
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pennsylvania Engineering Corp
Original Assignee
Pennsylvania Engineering Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pennsylvania Engineering Corp filed Critical Pennsylvania Engineering Corp
Priority to US05/557,415 priority Critical patent/US3956572A/en
Priority to DE19762609506 priority patent/DE2609506A1/de
Priority to CA247,553A priority patent/CA1062753A/fr
Priority to FR7606857A priority patent/FR2304046A1/fr
Priority to ZA761499A priority patent/ZA761499B/xx
Priority to JP51025175A priority patent/JPS51114306A/ja
Application granted granted Critical
Publication of US3956572A publication Critical patent/US3956572A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B7/00—Heating by electric discharge
    • H05B7/02—Details
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/12—Casings; Linings; Walls; Roofs incorporating cooling arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D9/00—Cooling of furnaces or of charges therein
    • F27D2009/0002—Cooling of furnaces
    • F27D2009/004—Cooling of furnaces the cooling medium passing a waterbox
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D9/00—Cooling of furnaces or of charges therein
    • F27D2009/0002—Cooling of furnaces
    • F27D2009/0056—Use of high thermoconductive elements
    • F27D2009/0062—Use of high thermoconductive elements made from copper or copper alloy

Definitions

  • This invention relates to electric furnaces and is more particularly concerned with cooling electric arc furnaces externally so as to minimize erosion of the refractory furnace lining resulting from localized heating and arc flaring.
  • the electrodes are held in spaced relationship with the molten bath in the furnace and an electric arc is drawn between the electrodes and the bath to provide heat for processing the metal.
  • Electric arc furnaces are variously designed for using one or more electrodes and the electrodes may be supplied with alternating or direct current.
  • Some arc furnaces use consumable electrodes of graphite or carbon and others use non-consumable electrodes which may be constructed of refractory materials and partially of metallic components on which the arc is struck.
  • the outer shell of the electric arc furnace is provided with a coolant chamber for taking the heat away from the shell and adjacent refractory lining as rapidly as possible.
  • prior art furnace cooling means have not been fully effective to minimize thermal deterioration and erosion since there is usually metal-to-metal contact between the cooling jacket and the furnace shell such that any irregularity between the interfacing surfaces produces interstices which are occupied by air which has poor thermal conductivity.
  • a primary object of the present invention is to provide a cooling means for the refractory lining of electric furnaces.
  • Another object is to provide a cooling means for electric furnaces which maximizes heat transfer from the refractory lining of the furnace to an externally applied coolant.
  • a further object is to provide a cooling means which is applicable to various kinds of electric furnaces and other metallurgical vessels as well.
  • the invention is characterized by the use of one or more cooling chambers in contact with the outer surface of the metal shell of the furnace or vessel.
  • the chamber has an inlet and outlet for coolant fluid.
  • the side of the chamber which is in contact relation with the shell of the furnace for conducting heat away from the refractory material on the other side of the shell preferably comprises a diaphragm or a flexible sheet of material which has good heat conductive properties.
  • the chamber is fastened to the metal shell in such manner that the space between the flexible sheet and the shell is leak proof. Before the chamber is attached, the sheet is preferably coated with a flowable or deformable heat conductive material.
  • Means are provided for evacuating the interspace between the sheet and the shell such that atmospheric pressure compels the sheet and the interfacing layer of flowable material to deform.
  • irregularities or voids at the interface are filled with the material and heat transfer is thereby enhanced because of the lack of discontinuities at the interface.
  • a single cooling chamber may be applied to each side of the furnace for more generalized cooling and in other cases where only particular zones need to be cooled, such as where arc flaring occurs, a plurality of cooling chambers may be distributed on the external surface of the furnace. Use of several chambers has the advantage of avoiding furnace shutdown in the event one of the chambers fails due to physical damage or the development of a leak.
  • FIG. 1 is a side elevation view, with parts broken away of the electric furnace showing the new coolant chambers applied to the exterior thereof;
  • FIG. 2 is a top plan view of the arc furnace illustrated in FIG. 1;
  • FIG. 3 is a vertical section of a coolant chamber taken on a line corresponding with 3--3 in FIG. 1;
  • FIG. 4 is an enlargement of a portion of the coolant chamber shown in FIG. 3.
  • FIG. 1 illustrates an electric arc furnace to which the new cooling means may be applied.
  • the furnace 10 includes an outer metallic shell 11 having a refractory lining 12.
  • refractory lining 12 may be composed of any suitable basic material such as magnesite or high alumina brick.
  • the lining may be silica brick or ground ganister mix.
  • the refractory bottom lining 13 of the vessel is dish shaped and serves as a hearth. The hearth supports a molten mass 14.
  • One side of the furnace has an opening 15 through refractory lining 12 and metal shell 11 which opening communicates with a pouring spout that is generally designated by the numeral 16.
  • Another side of the furnace has an opening 17 in front of which there is a door 18 that is movable upwardly from the position in which it is shown in FIG. 1 to permit introducing materials into the furnace through opening 17 and to permit raking slag from the furnace interior if desired.
  • the furnace also has a cover which is shown schematically and is designated generally by the reference numeral 19.
  • Three arcing electrodes 20, 21 and 22 are shown extending through suitable openings suchc as in the cover 19.
  • the means for energizing the electrodes are not shown nor are the means for supporting the electrodes so that they can be advanced and retracted with respect to the molten bath 14 to thereby establish an electric arc between the electrode and the bath.
  • the furnace illustrated in FIGS. 1 and 2 has three electrodes but it will be understood that the new cooling means may be used with arc furnaces may have one, two or more than three electrodes.
  • the cooling chambers according to the preferred embodiment of the invention are designated generally by the reference numerals 30,31 and 32 in FIGS. 1 and 2. Chambers 30, 31 and 32 are shown to be located on the outer surface of shell 11 and in an opposed relation relative to the electrodes 20, 21 and 22 respectively. These locations will normally be the hot spots of a three electrode furnace of the type illustrated. However, it will be appreciated that the number and location of each chamber will depend on the size of the vessel and the size and desired capacity of the cooling chambers which will be most propitiously located for absorbing heat where refractory hot spots are likely to exist. It should be understood for example that single large cooling chambers extending halfway around each side of the furnace from the pouring spout to the door may also be used.
  • cooling chamber 30 may comprise a hollow element 33 which defines a space through which coolant fluid may flow.
  • the hollow element 33 has a peripheral flange 34 for enabling the chamber to be enclosed by a cover 35.
  • the gasket between the margin of the cover 35 and flange 34 is not visible in FIG. 3 but it will be understood that the gasket may be clamped to effect sealing by bolts, not shown, passing through a plurality of bolt holes 36.
  • Hollow element 33 also has another flange 37 which is in contact relationship with the outer surface of furnace 11.
  • Flange 37 is welded all the way around where its corner terminates on the surface of outer shell 11.
  • the continuous weld is marked 38 and it will be understood to provide a leak proof joint between flange 37 and shell 11.
  • Coolant inlet and outlet pipes 39 and 41 are connected to element 32, coupled as can be seen in FIG. 2.
  • one, two or more coolant chambers such as 30 and 31 may be connected with a coolant input header 42 and the outlets from the chambers may be connected to a coolant fluid outlet header 43.
  • Flange 37 of hollow element 33 which contacts furnace shell 11 has a shallow recess 44 extending around its perimeter. The depth of this recess is substantially equal to the thickness of a thin sheet metal diaphragm 45. The margins of the diaphragm may be brazed or otherwise secured in a leak proof fashion within recess 44. Face 46 of flange 37 is substantially flush with outer face 47 of the thin diaphragm 45. A horizontal cross section of flange 37 and thin diaphragm 45 is not shown but it will be understood to have a curvature or other shape which permits the diaphragm to conform with the contour of furnace shell 11. The object is to get the maximum area of diaphragm 45 in contact relation with shell 11 to promote heat conductivity from shell 11 to coolant fluid in the hollow volume of the coolant chamber.
  • improved contact between diaphragm 45 and the outer surface of shell 11 is obtained by evacuating the interface region between the diaphragm and the shell after the coolant chamber is welded in a vacuum tight manner to the shell.
  • atmospheric pressure deforms the diaphragm and forces it to conform to the contour of the furnace shell so that area contact is increased.
  • deformable diaphragm 45 is provided with a pinch-off tube 50 which is shown in FIG. 3 and also is enlarged cross section in FIG. 4.
  • diaphragm 45 is provided with a hole 51 to which tube 50 is attached in a leak proof manner by brazing its end flange 52 to the surface of the diaphragm.
  • tube 50 is open ended to facilitate connecting it to a vacuum source, not shown.
  • the tube may be pinched off and sealed at its end 53 by techniques which are well known to those practicing vacuum technology.
  • a further feature of the invention is to improve heat transfer beyond what is obtainable by merely evacuating the interface between diaphragm 45 and shell 11 by using a flowable or deformable conductive coating 54 in the interface as is evident in the FIG. 4 enlargement.
  • This coating is applied to diaphragm 45 before the coolant chamber is welded to the shell.
  • the vacuum is drawn at the interface the diaphragm is compressed by the atmosphere and the coating material flows into the most minute void at the interface and forms a complete area contact having substantially no discontinuities or voids.
  • Any suitable material comprised of small particles of heat conductive material in a suitable binder for developing the desired consistency of the material may be used.
  • Colloidal sized particles of graphite or carbon are suitable. Such particles have an optimal average size of between 20 and 30 microns.
  • Other heat conductive particles may be used such as metallic particles or thermally conductive compounds such as the oxides of iron.
  • a suitable conductive mixture comprises about 40% of colloidal heat conductive material, 50% water and 10% inert fillers such as organic binders or clay. This mixture may be spread in a layer on the interfacing surface of thin deformable diaphragm 45 and dried to a large extent before it is fastened to shell 11.
  • Other suitable paste mixtures may comprise a filler such as starch, diatomaceous earth, silica and the like saturated with fine particles having good thermal conductivity.
  • the thin sheet of metal or diaphragm 45 may be copper, brass, low carbon steel or nickel. Other good metallic corrosion resistant materials may also be used.
  • the thickness of the diaphragm sheet will be governed to some extent by the strength of the material which is chosen. Generally the thickness will be about 0.005 inch to 0.050 inch but, as stated, the thickness can vary depending on the physical properties of the materials selected. In any case, the thickness should not be so great as to result in resistance to deformation under the influence of atmospheric pressure when the interspace is evacuated.
  • the flange may be provided with bolt holes for permitting the flange to be drawn tightly against the shell on stud bolts projecting from the latter to thereby enable pressing the thin metal diaphragm against the shell.
  • the diaphragm may be mounted in chamber in such manner that it is mechanically pressed into large area contact with the shell and the conductive coating may still be used on the interfacing surfaces.
  • a chamber may be so constructed and sized as to girdle an entire furnace of suitable configuration or it may be made in semi-sections which extend substantially halfway around the furnace. Hot spot formation in the refractory linings of a furnace are usually localized if more than one electrode is employed and those skilled in the operation and design of furnaces may readily determine the appropriate size and cooling capacity for a chamber and the most appropriate location thereof.
  • the new cooling device has been described in connection with an electric arc furnace, it will be understood that it is also applicable to other furnaces in which localized or even generalized overheating occurs. For instance, in open hearth furnaces where oxygen is injected through submerged tuyeres, localized hot spots may develop in the refractory side walls and roof.
  • the new cooling chamber may be suitably applied to cool these areas to prevent premature refractory deterioration as in electric arc furnaces.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Furnace Housings, Linings, Walls, And Ceilings (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Discharge Heating (AREA)
  • Furnace Details (AREA)
US05/557,415 1975-03-11 1975-03-11 Cooling means for electric arc furnaces Expired - Lifetime US3956572A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US05/557,415 US3956572A (en) 1975-03-11 1975-03-11 Cooling means for electric arc furnaces
DE19762609506 DE2609506A1 (de) 1975-03-11 1976-03-08 Lichtbogenofen
CA247,553A CA1062753A (fr) 1975-03-11 1976-03-10 Systeme de refroidissement pour four a arc
FR7606857A FR2304046A1 (fr) 1975-03-11 1976-03-10 Procede de refroidissement de la paroi externe d'une enceinte metallurgique et dispositif pour sa mise en oeuvre
ZA761499A ZA761499B (en) 1975-03-11 1976-03-10 Cooling means for electric arc furnaces
JP51025175A JPS51114306A (en) 1975-03-11 1976-03-10 Metallurgical furnace and how to cool same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US05/557,415 US3956572A (en) 1975-03-11 1975-03-11 Cooling means for electric arc furnaces

Publications (1)

Publication Number Publication Date
US3956572A true US3956572A (en) 1976-05-11

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ID=24225298

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/557,415 Expired - Lifetime US3956572A (en) 1975-03-11 1975-03-11 Cooling means for electric arc furnaces

Country Status (6)

Country Link
US (1) US3956572A (fr)
JP (1) JPS51114306A (fr)
CA (1) CA1062753A (fr)
DE (1) DE2609506A1 (fr)
FR (1) FR2304046A1 (fr)
ZA (1) ZA761499B (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1980001000A1 (fr) * 1978-11-07 1980-05-15 K Sharp Refroidissement de surfaces adjacentes a du metal en fusion
US6198293B1 (en) * 1998-03-26 2001-03-06 Massachusetts Institute Of Technology Method and apparatus for thickness measurement using microwaves
US20170304924A1 (en) * 2016-04-20 2017-10-26 The Hong Kong Polytechnic University Magnetic-Aided Electrospark Deposition

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3743752A (en) * 1971-02-02 1973-07-03 Daido Steel Co Ltd Method of suppressing hot spot in arc furnace and apparatus therefor
US3777043A (en) * 1973-01-17 1973-12-04 Neill Corp O Apparatus and method for cooling a refractory lining
US3829595A (en) * 1972-01-25 1974-08-13 Ishikawajima Harima Heavy Ind Electric direct-arc furnace

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1111657B (de) * 1958-02-11 1961-07-27 Didier Werke Ag Verfahren und Moertel zum Einbau von Kuehlkaesten in das Mauerwerk von Hochoefen od. dgl. Schachtoefen

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3743752A (en) * 1971-02-02 1973-07-03 Daido Steel Co Ltd Method of suppressing hot spot in arc furnace and apparatus therefor
US3829595A (en) * 1972-01-25 1974-08-13 Ishikawajima Harima Heavy Ind Electric direct-arc furnace
US3777043A (en) * 1973-01-17 1973-12-04 Neill Corp O Apparatus and method for cooling a refractory lining

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1980001000A1 (fr) * 1978-11-07 1980-05-15 K Sharp Refroidissement de surfaces adjacentes a du metal en fusion
US6198293B1 (en) * 1998-03-26 2001-03-06 Massachusetts Institute Of Technology Method and apparatus for thickness measurement using microwaves
US20170304924A1 (en) * 2016-04-20 2017-10-26 The Hong Kong Polytechnic University Magnetic-Aided Electrospark Deposition
US10610950B2 (en) * 2016-04-20 2020-04-07 The Hong Kong Polytechnic University Magnetic-aided electrospark deposition

Also Published As

Publication number Publication date
ZA761499B (en) 1977-04-27
JPS51114306A (en) 1976-10-08
FR2304046A1 (fr) 1976-10-08
DE2609506A1 (de) 1976-09-30
CA1062753A (fr) 1979-09-18
FR2304046B1 (fr) 1980-01-25

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